1. Field of the Invention
The present invention relates to dinitro compounds and diamino compounds, and in particular, to dinitro compounds and diamino compounds which are useful as starting or intermediate materials for preparing organic photoconductive materials for use in electrophotography, and preparation methods thereof. The present invention further relates to triamine compounds which are useful as organic photoconductive materials for use in electrophotography and a preparation method thereof.
2. Discussion of Background
A two-layered type electrophotographic photoconductor, one type of electrophotographic photoconductors, is widely used in the field of electrophotography. As conventionally known, the above-mentioned two-layered type electrophotographic photoconductor is constructed in such a manner that (i) a charge generation layer comprising a charge generating material capable of generating charge carriers when exposed to light, and (ii) a charge transport layer comprising a charge transporting material capable of efficiently injecting the above-mentioned charge carriers in the charge transport layer and transporting the same, are successively overlaid on an electroconductive support.
It is conventionally known that various azo compounds are effective as the charge generating material in the above-mentioned two-layered type electrophotographic photoconductor. For example, benzidine type bisazo compounds in Japanese Laid-Open Patent Applications 47-37543 and 52-55643; stilbene type bisazo compounds in Japanese Laid-Open Patent Application 52-8832; diphenylhexatoriene type bisazo compounds in Japanese Laid-Open Patent Application 58-222152; and diphenylbutadiene type bisazo compounds in Japanese Laid-Open Patent Application 58-222153 are well known.
On the other hand, various kinds of the charge transporting materials, which are to be contained in the charge transport layer of the two-layered type electrophotographic photoconductor in the electrophotographic process, are also conventionally proposed. For example, poly-N-vinylcarbazole and triphenylamine compounds are disclosed in U.S. Pat. No. 3,180,730; and benzidine compounds are disclosed in U.S. Pat. No. 3,265,496, Japanese Patent Publication 39-11546 and Japanese Laid-Open Patent Application 53-27033.
The above-mentioned electrophotographic process is one of the image forming processes, in which the surface of the photoconductor is charged uniformly in the dark to a predetermined polarity, for instance by corona charge. The uniformly charged photoconductor is exposed to a light image to selectively dissipate the electrical charge of the exposed areas, so that a latent electrostatic image is formed on the photoconductor. The thus formed latent electrostatic image is developed by a developer to a visible image.
Fundamental characteristics required for the photoconductor in such an electrophotographic process are: (1) chargeability to an appropriate potential in the dark, (2) minimum dissipation of electrical charge in the dark, and (3) rapid dissipation of electrical charge when exposed to the light.
However, the conventional organic photoconductive materials do not necessarily satisfy the above electrophotographic characteristics at the same time.